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How are Infectious Diseases Studied and Treated?

How are Infectious Diseases Studied and Treated?

Image: Adobe Stock / metamorworks

A novel pathogen is sort of a “black box” for scientists. Initially, little is known about how the pathogen spreads and what health consequences an infection may have for humans. Substantial research and development investment is needed to develop tests, vaccines, and drugs to contain pandemics and treat diseases. Despite all scientific advances in medicine, it is not always possible to develop a vaccine for every new infectious disease.

What is the procedure in diagnostics?

Any person who has become infected with a virus or bacterium must be isolated quickly to prevent further infections and to interrupt infection chains. Sometimes it is difficult to assign the symptoms precisely. The bubonic plague symptoms are initially similar to flu-like symptoms, while those of pneumonic plague are similar to severe pneumonia. Only a medical test can provide an exact diagnosis.

The challenge with new types of pathogens is that there are no tests in the beginning. Researchers must first analyze the pathogen, learn about its properties, and develop tests based on this knowledge. It took two years to discover the pathogen in HIV/AIDS after the disease was first described on 5 June, 1981, by the U.S. Centers for Disease Control and Prevention in Los Angeles (May 1983) and another two to three years until the first reliable tests were available.

Virologist Helga Rübsamen-Schaeff on the varying significance of tests: “HIV is not about chains of infection.” (German, English translation below)

Virologist Helga Rübsamen-Schaeff on research into HIV: “With AIDS, it was very quickly concluded that it is an infection.” (German, English translation below)

With a test, the human organism – for example, in the mucous membranes or the blood – is searched for cues to the pathogen or specific antibodies that the immune system forms against viruses or bacteria. If the result is positive and the person is infected, he or she must remain in isolation until being healthy again, unless the pathogen remains in the body permanently, as is the case with HIV. In addition, people with whom the infected person has had contact must be informed, tested, and isolated if necessary and feasible.

Maintain social distance – hope for a vaccine

To contain the further spread of a virus, specific rules of conduct apply during a pandemic. If the pathogen is spread via the respiratory tract, people should keep their distance. In some cases, events are canceled, and facilities such as childcare centers and schools are closed. This is intended to mitigate the dynamics of the pandemic. In most cases, there are still no specific drugs or vaccines against a new virus.

Vaccinations are the most important measures to protect yourself from an infectious disease. They work on two levels: Since they reduce the further spread of the pathogens, they protect both the vaccinated person (individual protection) and society as a whole (community or herd protection). Infectious diseases such as measles, diphtheria, poliomyelitis (polio) were still widespread decades ago but could be contained by vaccination programs. Smallpox was successfully combated for years through worldwide vaccination programs. According to the WHO, the disease has been considered eradicated since 1979.

Lengthy development period, high costs

The task of research is to develop a vaccine as quickly as possible when a new pathogen breaks out. The clinical development until approval can take up to 15 years and costs billions of euros. Therefore, research and development are carried out both in publicly funded institutions and by the pharmaceutical industry. Before a vaccine is approved, it must pass three time- and cost-intensive phases where research proves its safety and efficacy.

Virologist Helga Rübsamen-Schaeff on the development of vaccines: “First, it's all about safety and tolerability.” (German, English translation below)

Virologist Helga Rübsamen-Schaeff on the challenge of vaccine development: “Every virus is different.” (German, English translation below)

After the laboratory development period, only a few people are initially tested during the first phase of a clinical trial. The main objective is to determine whether the vaccine is free of harmful side effects. Up to a thousand test persons are already involved in phase two. Here, the required dosage and protective effects are tested additionally. In the third phase, specific vaccination regimens are verified, and it is examined whether age- or gender-specific differences exist.

Live-attenuated or inactivated vaccines are used for measles and influenza. The virus is thereby injected in either attenuated or inactivated form. These substances train the immune system to fend off the pathogens successfully. Scientists are now also working on new types of vaccines that activate the immune system in different ways to combat pathogens.

It is not always possible to develop a vaccine. For example, there are no vaccines against HIV and malaria, although science and industry have been searching intensely for them worldwide and invested large amounts of money. Sometimes diseases can be controlled quite well without a vaccine. There are preventive drugs against malaria. There are also various drugs against HIV, which help infected people to live a long life. Some of these drugs are also used to protect against infection.

Virologist Helga Rübsamen-Schaeff on why there is no vaccine against HIV: “The virus is highly variable.” (German, English translation below)

Vaccines or drugs to be administered in Germany require national approval or approval from the European Commission. Only then is any drug or vaccine available to the entire population. The Paul Ehrlich Institute (PEI) is responsible for the approval of biological drugs and vaccines in Germany. It monitors their quality, efficacy, and safety. At the PEI there is also a WHO Collaborating Center for the standardization and evaluation of vaccines. The European Medicines Agency (EMA) coordinates the European marketing authorizations.

Virologist Helga Rübsamen-Schaeff on the development of drugs against COVID-19: “Reducing viruses in the body as early as possible.” (German, English translation below)



Caroline Wichmann

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